The present invention relates to balloon anchors for anchoring medical devices in a body lumen, and, in particular, to a balloon anchor for positioning a catheter or similar device within the heart.
Many abnormal medical conditions have resulted in disease and other aberrations along the lining or walls of a cavity or lumen within the body. Catheterization is a type of procedure performed for a wide variety of purposes, including vascular access for performing diagnostic, interventional, and therapeutic procedures. For example, cardiac catheters are inserted through blood vessels into a patient""s heart to detect cardiac electrical signals, to apply electrical stimulation for diagnostic testing and to apply energy. Such energy can take the form of heat, electric current or radiation in order to eliminate (i.e. xe2x80x9cablatexe2x80x9d) the source of an arrhythmia. Other applications for ablation catheters include the treatment of tumors, such as breast or liver tumors, and the treatment of other aberrant biological structures. The catheter can also include other structures, such as a lumen through which chemical agents are delivered, mapping electrodes, and/or a sampling system for sampling a tissue or fluid specimen.
Current procedures include laparoscopic, endoluminal, perivisceral, endoscopic, thoracoscopic, intra-articular and hybrid approaches. Access into the body is made through a small incision. A catheter may be inserted at the incision into the cavity or working space and advanced through the lumen until it is positioned correctly. It is generally necessary to utilize a visualization technique of some sort in order to guide the catheter to a desired site of diagnosis and/or treatment and to ensure that the catheter remains at the desired location. Additionally, it is sometimes desirable or necessary to re-position the catheter at a particular location.
However, once the catheter is placed at the operative site, it is often desirable to fix the catheter at that position. Balloon structures are known in the art as mechanisms for anchoring a catheter in place. The balloon is inflated with fluid while the instrument is within the lumen. Once inflated, the balloon is engaged in direct contact with a wall of the lumen. The procedure is then performed. Once completed, the fluid is removed from the balloon, thereby deflating the balloon and allowing the catheter to be removed.
Although various designs of balloon anchored catheters have been quite useful, they often suffer from one or more limitations. In particular, it is difficult to know when an anchoring balloon is properly inflated. Because lumen dimensions will vary from one patient to another, it is sometimes impossible to predict how much fluid should be used to inflate the balloon. Under inflation of the balloon will result in a less than optimal anchorage of the instrument. On the other hand, over inflation of the balloon can damage the lumen. Moreover, when the balloon is large the wall tensions of the balloon are increased and there is a significant chance of balloon rupture. Additionally, balloons serve as total roadblocks to the passage of fluids, including but not limited to blood.
Consequently, there is a need for an anchoring balloon device that prevents over or under expansion of the balloon while providing irrigation to the lumen to locally reduce hematocrit and the chance of clotting.
The present invention is directed to an anchoring balloon structure for use with catheters. The anchoring balloon structure contains an expandable balloon disposed about a port on a catheter and a valve for regulating the pressure in the balloon while at the same time for providing irrigation to a body lumen. The balloon, when filled with fluid, expands and is engaged in direct contact with the tissue. Once the balloon is engaged, any additional inflation fluid will be released by the valve, thus regulating the pressure and also, optionally, providing irrigation at a treatment site (e.g. so that blood can be cleared from an ablation site). The balloon can be deflated by applying a vacuum which removes the fluid from the balloon. The valve prevents any back diffuision of external fluids thereby allowing the balloon to become ally deflated. Once fully deflated, the balloon can be easily removed from the body lumen.
In one embodiment, the valve is a pressure-relief valve connected to a second port in the catheter. The first and second ports are in communication with each other and with a single source of fluid. For example, a simple valve can be formed by surrounding the catheter body (and the second port) with an elastomeric sleeve. The sleeve covers the second port so as to force the fluid to enter the first port and fill the balloon. Once the balloon is full, the pressure of the balloon against the tissue is equal to or greater than the pressure of the sleeve over the second port. Any additional fluid is then forced into the second port and pushed out of the sleeve to irrigate the lumen.
In another embodiment, the pressure-relief valve comprises an elongated slit in the catheter. When the balloon is expanded, the pressure exerted on the expanded balloon causes the elongated slit to open and release fluid into the lumen. The pressure-relief valve can further comprise a fluid diff-using sleeve or a second expandable fluid diffusing balloon disposed over an elongated slit or a second port.